1. Field of the Invention
The present invention relates to a rotor for a rotary adsorber of the type in which a partitioning plate mounted on the case defines the end surface of the rotatably held rotor into at least an adsorbing zone, a recycling zone, and a cooling zone, and more specifically, to a rotor for rotary adsorbers provided with arc-shaped sectors formed of a gas adsorptive element of honeycomb construction having a number of small through holes in the cylindrical rim partitioned by spokes radially extending therein into arc-shape portions in cross section, and having calking material interposed between the mating surfaces of these sectors and the combination of the spoke and rim.
Furthermore, the present invention relates to a sealing device for sealing between the end surface of a rotor and a partitioning frame of a casing of the rotary adsorber that clarifies gas containing an organic solvent by passing the same between end surfaces of the rotatable rotor including an adsorptive element to allow the adsorptive element to adsorb an organic solvent and blowing a hot air in the opposite direction to separate and blow off the organic solvent adhered on the absorptive element to recover the adsorptive element to the state in which it can be reused.
2. Description of the Related Art
Referring now to FIGS. 11 to 14, the structure of the rotor for rotary adsorbers of the related art will be illustrated. FIG. 11 is a perspective view showing a principal portion of the rotary adsorber having a rotor rotatably held therein, FIG. 12 is a perspective view of the rotor, FIG. 13 is a cross sectional view of FIG. 12 taken along the line Axe2x80x94A showing seal-mating surfaces of each arc-shaped sector and the spoke, and FIG. 14 is a partially exploded perspective view showing the entire construction of the rotor including the outer peripheral rim 507.
In the rotary adsorber 500 specifically for an organic solvent provided with a conventional adsorptive element 504, adsorbed organic solvent has been removed by rotating the rotor 501 in the holding case 510 that is divided into an adsorbing zone S, a cooling zone T, and a recycling zone U, thereby temporarily defining an adsorbing zone and a recycling zone on one of the end surface of the rotor, adsorbing the organic solvent contained in gas onto the adsorbing element 504 carried by the rotor 501 when the surface of the rotor passes through the adsorbing zone S, and allowing recycling air heated to the temperature higher than 180xc2x0 C.-200xc2x0 C., which is a boiling point of an organic solvent, to pass through the adsorptive element 504 from the end surface opposite from the end surface in the recycling zone U.
Among gases containing an organic solvent, a gas generated in the manufacturing process of semi-conductor components, for example contains organic solvents such as DMSO (dimethyl sulfoxide), MEA (monoethanol amine), HMDS (hexamethilenedisilazane), and so on. These organic compounds cannot be removed sufficiently at a recycling temperature of 180 to 200xc2x0 C. Therefore, such organic compounds are increasingly accumulated on the rotor, which may result in deterioration of performance or burning of the rotor. In order to remove such organic compounds, it is required to send hot air heated to about 200-350xc2x0 C. to the rotor 501 at the recycling zone U.
The rotor 501 of honeycomb construction integrally formed into a cylindrical shape by combining a plurality of arc-shaped sectors 502 is reinforced by a plurality of metallic spokes 503 extending radially outwardly from the hub 505. The metallic spoke and the sectors 502 of honeycomb construction are joined or bonded by the use of heat resistant calking material 508 such as silicone. In addition, the metallic outer peripheral rim 507 for protecting the outer periphery of the rotor 501 and the honeycomb construction 504 itself are also bonded via a calking material 508 of silicone.
As described above, the rotor 501 is rotatably mounted to the holding case 510, and the partitioning plates 511 for defining the adsorbing zone S, the recycle zone U and the cooling zone T are provided with seal (not shown) formed of silicone rubber with PTFE film applied thereon so as to slidably press against the end surface of the rotor 501 to prevent leakage or mixing of gas passing therethrough.
When attempt was made to send a hot air over 200xc2x0 C. as described above to the rotor of such a structure for recycling, since a calking material of silicone or rubber could not resist such a high temperature, silicone or rubber was deteriorated and thus the joining performance or adhering performance between the spoke and the rotor was lowered, whereby the arc-shaped sectors constituting the rotor might fall off so that the rotor itself could not be used any more.
Therefore, there was a limit on the temperature of the air to be passed through, and thus the accumulated high boiling organic solvent or polymer could not be removed sufficiently. As a consequence, the cleaning performance was lowered, or when using the solvent that can be polymerized within the rotor in which the solvent is accumulated, it could not be recycled and the polymer gave damage to pores of the adsorptive element like zeolite, thereby lowering the cleaning performance as an adsorptive element.
Next, a conventional sealing device for a rotary adsorber is discussed. As discussed above, an organic solvent adsorber rotatably holds a rotor by a motor in a box-shaped casing having partitioning frame for dividing the surface of the rotor into an adsorbing zone, a recycling zone, and a cooling zone. On the other hand, the rotor includes an adsorptive element forming a plurality of fan-shaped sectors defined by a metallic cylindrical rim, which has a honeycomb construction in which a plurality of pores pass through from one end surface to the other end surface, and has the plurality of fan-shaped sectors inserted in fan-shaped spaces defined by radially extending metallic spokes.
In the actual use, when a gas containing an organic solvent is blown onto the portion of one of the end surfaces of the rotor positioned at the adsorbing zone toward the other end surface thereof, an organic solvent contained in gas is adsorbed and clarified gas is discharged from the other end surface, and the rotor is rotated by a prescribed angle to move from the adsorbing zone to the recycling zone, and then the organic solvent adsorbed thereon is removed by separating and blowing off bypassing a recycling air heated to the temperature higher than 180xc2x0 C. to 200xc2x0 C. that exceeds the boiling point of the adsorbed organic solvent from the other side to the one side to recycle the adsorptive element.
In addition, the partitioning frame defining these adsorbing zone and the recycling zone on the end surface of the rotor also includes at least three radially extending partitioning plates and an annular plate or an arc shaped plate facing toward the outer peripheral portion of the end surface of the rotor and defines each fan-shaped zone by being combined with the outer end portion of the partitioning plates.
These partitioning plates are further provided with sealing strips or resilient sealing blocks facing the end surface of the rotor so as to be slidable toward the end surface for preventing mutual interference of air in each fan-shaped zone. Such kind of seal has a disadvantage in that it cannot establish complete sealing performance in the cases where flatness of the end surface of the rotor is not satisfactory as the first problem, and where the end surface of the rotor during rotation does not form a plane exactly perpendicular with respect to the axis of rotation as the second problem.
Especially in the rotary gas adsorber of the type described above, there is a problem in that the rotor develops deflection during rotation so that the end surface of the rotor does not form a perpendicular plane at an exact right angle with respect to the axis of rotation. In addition, these sealing strips or resilient sealing blocks require heat resistance, wear resistance and chemical stability.
Accordingly, it is a first object of the present invention to provide a rotor for rotary adsorbers provided with a thermal insulating seal that can well resist a high temperature exceeding 200xc2x0 C. for protecting a calking material applied to the joint portion.
Furthermore, it is a second object of the present invention to provide a sealing device that can establish good sealing performance all the time while following the pits and projections on the surface of the rotor irrespective of the flatness or perpendicularity of the end surface of the rotor in order to overcome the problems described above.
According to the present invention, the first object described above can be achieved by a thermal insulating seal of a plate-shaped incombustible material that covers an end surface of the spoke and the joint portion between the two arc-shaped sectors coming into contact with both sides of the end surface. The thermal insulating seal is mounted on the end surface in parallel with the end surface. This arrangement prevents a heated hot recycling air from being blown directly onto the joint portion between the sectors and the spoke, and thus prevents increase in temperature of calking material, thereby preventing lowering of sealing property or adhering force due to deterioration of calking material. Simultaneously, a hot air is blown onto the adsorptive element other than the portion of the thermal insulating seal, so that a boiling organic solvent or polymer adhered to the adsorptive element is separated and blown off, thereby preventing lowering of adsorbing performance when the adsorptive element itself is reused.
According to a preferred embodiment of the rotor for rotary adsorbers of the present invention, the thermal insulating seal is mounted via a mounting plate welded on the end surface of the spoke. In this arrangement, complex molding process for mounting the thermal insulating seal plate directly on the spoke may be avoided, and replacement thereof can easily be performed.
According to another preferred embodiment of the rotor for rotary adsorbers of the present invention, the thermal insulating seal is secured to the mounting plate by a screw. This arrangement significantly facilitates replacement of the thermal insulating seal.
According to still another preferred embodiment of the rotor for rotary adsorbers of the present invention, the thermal insulating seal extends from the peripheral edge of the rim onto the end surface of the rotor. This arrangement generally prevents a hot air from being blown directly to a calking material between the metallic rim and the outer peripheral surface of the arc-shaped sector, thereby preventing deterioration of a calking material.
According to a further preferred embodiment of the rotor for rotary adsorbers of the present invention, the thermal insulating seal is a silicon nitride plate. In this arrangement preferable, thermal insulating effect is obtained and simultaneous durability of the plate of incombustible material itself is ensured, thereby preventing deterioration of its performance even after many hours of service and having excellent thermal insulating effect.
According to still a further preferred embodiment of the rotor for rotary adsorbers according to the present invention, the thermal insulating seal is a laminated body in which a metal plate is overlaid on a sheet of expanded black lead. In this arrangement, since a sheet of black lead has high heat resistance, and in addition, a metal plate is overlaid thereon, a sheet of expanded black lead, which is fragile in itself, is protected to ensure high toughness and durability, whereby an excellent thermal insulating effect is maintained for a long time.
According to an additional preferred embodiment of the rotor for rotary adsorbers of the present the invention, a heat insulating material is interposed between the mounting plate and the thermal insulating seal. This arrangement alleviates heat transferred to the joined surfaces via the spoke that is exposed to a hot air to some extent by providing a heat insulating material, and a calking material is further protected from a high temperature.
According to another preferred embodiment of the rotor for rotary adsorber of the present invention, the heat insulating material is a calcium silicate plate. This arrangement ensures an excellent heat insulating effect between the heated plate of incombustible material and the mounting plate mounted to the spoke, thereby ensuring protection of a calking material from heat. In the construction of the rotor for rotary adsorber according to the present invention described above, it is preferred to employ silicone resin or fluorine-contained rubber having adhesive property as a calking material.
According to the present invention, the second object described above can be achieved by a sealing device mounted on a partitioning frame fixed to a casing of a rotary gas adsorber for defining at least an adsorbing zone and a recycling zone on the end surface of a rotatable rotor so as to be slidable with respect to the end surface of the rotor. Incombustible sealing material is interposed between the partitioning frame and a mounting plate extending in parallel from the partitioning frame so as to be slidable toward the end surface of the rotor; the mounting plate is fixed to the partitioning frame via a connecting portion; the sealing material is provided with a cylinder hole therein and held by a rod member having an engaging portion extending into the cylinder hole at the tip portion and fixed to the connecting portion with a screw at the rear end thereof so as to be movable along the rod member; and a spring enclosing the rod member is interposed between the sealing material and the connecting portion to resiliently urge the sealing material toward the end surface of the rotor.
In the structure described above, the sealing material, being formed of incombustible material, is not deformed by heat, even when it is brought into contact with the rotor which is exposed to a hot air. In addition, even when the rotor develops deflection during rotation, the sealing material can follow such deflection and be kept in contact with the end surface of the rotor since a resilient force is always applied to the sealing material. Therefore, sealing performance of each zone can be established all the time.
In a preferred embodiment of the present invention, the sealing material is formed of expanded black lead. Since this material has a high heat resistance, it is preferable to use sealing material formed of a material superior in heat resistance and being chemically stable because a hot air flow at the temperature higher than its boiling point of 180-200xc2x0 C. is blown to the rotor especially at the time of treating gas containing an organic solvent.
In another preferred embodiment of the present invention, the sealing material is graphite. Since this material also has high heat resistance and is superior in wear resistance and in chemical stability, it is quite preferable to use the sealing material in the environment described above.
In a preferred embodiment of the present invention, a resilient sheet strip is inserted between the sealing material and either one or both of the partitioning frame and the mounting plate which hold the sealing material therebetween. Resiliently interposing the sealing material in such a manner serves to absorb the impact applied to the sealing material by the partitioning frame and the mounting plate when the sealing material is subject to an impact during sliding movement on the end surface of the rotor.
In a preferred embodiment of the present invention, the resilient sheet strip is formed of expanded black lead. As characteristics of this material, it is, as a matter of course, superior in heat resistance as described above, but in contrast to it, it is inferior in mechanical strength. Therefore, in order to compensate this disadvantage, expanded black lead having resiliency in addition to heat resistance is preferably used for sealing material. Since expanded black lead is superior in wear resistance in itself, inserting such a resilient sheet strip of expanded black lead between the sealing material and the partitioning frame and mounting plate makes the movement of the sealing material following the end surface of the rotor smoother.